Standardize usage of virtual/override/final in extensions/

extensions/browser/extension_system.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef EXTENSIONS_BROWSER_EXTENSION_SYSTEM_H_
 #define EXTENSIONS_BROWSER_EXTENSION_SYSTEM_H_
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
@@ skipping 37 matching lines @@
 class StateStore;
 class WarningService;
 
 // ExtensionSystem manages the lifetime of many of the services used by the
 // extensions and apps system, and it handles startup and shutdown as needed.
 // Eventually, we'd like to make more of these services into KeyedServices in
 // their own right.
 class ExtensionSystem : public KeyedService {
  public:
   ExtensionSystem();
-  virtual ~ExtensionSystem();
+  ~ExtensionSystem() override;
 
   // Returns the instance for the given browser context, or NULL if none.
   static ExtensionSystem* Get(content::BrowserContext* context);
 
   // Initializes extensions machinery.
   // Component extensions are always enabled, external and user extensions are
   // controlled by |extensions_enabled|.
   virtual void InitForRegularProfile(bool extensions_enabled) = 0;
 
   // The ExtensionService is created at startup.
@@ skipping 74 matching lines @@
 
   // Get the user script master for declarative scripts, if any.
   virtual DeclarativeUserScriptMaster*
       GetDeclarativeUserScriptMasterByExtension(
           const ExtensionId& extension_id) = 0;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_SYSTEM_H_